My car was too cheap to have an electric liftgate, though I don’t know if I can open it with a dead battery - never tried, and never had a battery so dead it needed replacing that urgently. Very possible it doesn’t open with a dead battery though, at least if the vehicle is locked when the battery dies.
Nah, a lot of school life manga cover this, at least briefly, especially with female authors. It tends to be kept brief or referenced off screen however, to avoid needing to censor or change the rating.